A discussion of the role of developmental psycholinguistics in second language instruction begins by examining the nature of communicative intentions, their classification, and their role in the language classroom, drawing parallels between first language acquisition and second language learning. Stages in the progression from single words to sentences and in the acquisition of some morphosyntactic elements are outlined, in each case examining how these are manifested at different grade levels, in the school context. Principles of educational psychology are then applied to classroom interaction, particularly as they have implications for choice of educational goals and for group work. The second part of the book reports on a three-year experiment using a developmental psychology approach in English and German second language classes in grades 3-5 of an Italian school. Class activities and teaching formats are described, and the use and results of both interviews and achievement tests to assess student learning are discussed. Contains 123 references and subject and author indexes. (MSE)